Carbon monoxide deaths predictably follow every major weather-related power outage. Experts say these fatalities are preventable. ProPublica, The Texas Tribune and NBC News investigate.

The story was also produced in partnership with NBC News.

AUSTIN — More than five hours into a legislative debate on voting restrictions and border security last week, a Texas lawmaker made a last-ditch attempt to strengthen the state’s power grid and, in the process, prevent carbon monoxide deaths.

On Aug. 27, state Rep. Erin Zwiener, a Democrat from Driftwood, just outside of Austin, offered an amendment that would redirect $250 million from a $1.8 billion border security bill to improve the reliability of the power grid. The measure, she told her colleagues, could keep “our citizens from dying during a winter storm from carbon monoxide poisoning.”

Zwiener’s amendment came months after an April investigation by ProPublica, The Texas Tribune and NBC News found that a weeklong February storm that left millions of residents without power had also resulted in the largest carbon monoxide poisoning event in recent U.S. history. At least 17 people were killed by the gas and more than 1,400 were hospitalized.

The investigation revealed weak links at every level of government, including that the state failed to regulate the power grid and lawmakers repeatedly declined to act on legislation that would have required carbon monoxide alarms in residences.

“There were a lot of people taking risks to try and stay warm enough. We’re honestly lucky we lost as few people as we did to carbon monoxide poisoning,” Zwiener said in a recent interview, adding that she had the news organizations’ latest installment of the investigation in mind when she proposed the amendment.

The amendment failed. The author of the border bill, state Rep. Greg Bonnen, a Republican from Friendswood, said he opposed taking funding away from border security.

In the six months since the storm, lawmakers have not taken any sweeping action to protect most Texas residents from carbon monoxide poisonings at home.

In June, Gov. Greg Abbott, a Republican, signed into law a more limited measure updating the state’s building codes, which would require carbon monoxide alarms in homes that are built or renovated starting in 2022. The requirement wouldn’t apply to unincorporated areas unless counties choose to adopt the new standards, and cities could opt out of the provision.

Most significantly, the new law does not require carbon monoxide alarms in the state’s nearly 10 million existing homes and apartments.

Public health experts warn that more needs to be done to protect residents’ lives.

Requiring carbon monoxide alarms in newly constructed homes “helps stop the bleeding,” said John Riddle, president of the Texas State Association of Fire Fighters, but “it would take years and years and years” for carbon monoxide alarms to be installed in the vast majority of homes across the state. Riddle said that, at a minimum, existing homes with gas-fired appliances that produce carbon monoxide should have the devices.

Before the legislative change, Texas was one of six states without any statewide requirements for carbon monoxide alarms. The new law still leaves Texas with weaker regulations than 29 other states that require the devices in existing residences.

Carbon monoxide poisonings often follow storms or other natural disasters in which people lose power and seek alternative sources for electricity, including generators and cars. And climate change is contributing to more severe storms, such as hurricanes, scientists say, making the danger more common.

Days after Zwiener’s amendment was defeated in Texas, Hurricane Ida pummeled Louisiana, knocking out power for more than 1 million people, leading to at least four carbon monoxide poisoning deaths and sending nearly four dozen residents to the hospital after they were exposed to the gas. Louisiana, like Texas, requires carbon monoxide alarms only in newly constructed or recently renovated homes.

“The storm-related interruptions in power supply will result in additional epidemics of carbon monoxide poisonings, similar to what occurred in Texas in February of this year,” Dr. Kelly Johnson-Arbor, co-medical director at the National Capital Poison Center and an expert in carbon monoxide poisoning, said Thursday in an interview.

Johnson-Arbor is among the public health and fire safety experts who recommend that every home — not just newly constructed or renovated residences — be equipped with a carbon monoxide alarm. The alarms are inexpensive and are the only way to detect the colorless, odorless gas.

The regular legislative session ended in May, and only Abbott has the power to call a special session and to decide what issues lawmakers will address during that window. The governor has so far required lawmakers to return for two 30-day special sessions, but his agenda has not focused on the winter storm. Instead he has asked legislators to tackle partisan priorities like border security — including the state-led construction of a wall along the U.S.-Mexico border — voting restrictions and banning transgender youths from joining school sports teams that match their gender identity.

Abbott did not respond to requests for comment.

The latest special session ended Thursday. If the governor does not include broader carbon monoxide measures in another special session, the earliest chance for lawmakers to act would be in 2023.

“If we don’t take action, people will lose their lives,” said state Sen. José Menéndez, a Democrat from San Antonio.

The lack of a strong statewide regulation has created a patchwork of local policies across Texas. Some of the state’s most populous cities and counties require carbon monoxide alarms to be installed in existing buildings, but even those regulations have gaps, experts said.

For example, Austin voted in 2017 to become the first major city in Texas to require carbon monoxide alarms in all residences with gas-fired appliances or attached garages, but the city’s inspectors typically just check existing buildings for the alarms following renters’ complaints, said Moses Rodriguez, a supervisor in Austin’s code enforcement office. Last year, Austin recorded only 36 violations for carbon monoxide alarms that were missing, improperly located or relying on an incorrect power source in rental properties, according to the city’s code department. Austin homeowners must also comply with the law, but owner-occupied homes are usually not subject to inspections.

In Harris County, which includes Houston, at least five people died and about 600 people were hospitalized for carbon monoxide poisoning during the February storm.

Harris County Judge Lina Hidalgo, who during the winter storm called the carbon monoxide poisonings a “disaster within a disaster,” said her office is discussing steps to “make carbon monoxide detectors commonplace across our county.”

“Our infrastructure and regulatory framework wasn’t built to stand up to the relentless impacts of a winter storm, and that was made all too clear with the tragic fatalities we witnessed due to carbon monoxide poisoning,” Hidalgo wrote in an email. “Sadly, these tragedies can be prevented.”

Rafael Lemaitre, a spokesperson for Hidalgo, said that because of the risk of prolonged power outages, the discussions are just as pressing now, as hurricane season ramps up, as they were after the winter storm.

Harris County Fire Marshal Laurie Christensen said that in November the Texas Fire Marshals Association will discuss what potential changes to state law the group can support during the 2023 legislative session to help prevent widespread poisonings.

“We, in this part of the country, have failed to really push carbon monoxide poisoning because it wasn’t something we saw that often,” Christensen said, referring to the need for more education about prevention and alarms. “And unfortunately we’re realizing now that that is going to be a key factor.”